1. Technical Field
The present invention relates to an inspection system that inspects the edge of a semiconductor wafer or like substrate such as a microelectronics substrate.
2. Background Information
Over the past several decades, the semiconductor has exponentially grown in use and popularity. The semiconductor has in effect revolutionized society by introducing computers, electronic advances, and generally revolutionizing many previously difficult, expensive and/or time consuming mechanical processes into simplistic and quick electronic processes. This boom in semiconductors has been fueled by an insatiable desire by business and individuals for computers and electronics, and more particularly, faster, more advanced computers and electronics whether it be on an assembly line, on test equipment in a lab, on the personal computer at one's desk, or in the home electronics and toys.
The manufacturers of semiconductors have made vast improvements in end product quality, speed and performance as well as in manufacturing process quality, speed and performance. However, there continues to be demand for faster, more reliable and higher performing semiconductors. To assist these demands, better inspection is necessary to increase yields. One area that has been generally ignored is the edge of the semiconductor wafer, and it is believed that inspection of such edge area will lead to better information on defects, thereby enabling improved process control and improved wafer yields.
In the past, when attempts to inspect the wafer edge were made, the inspection was generally performed manually with the naked eye of a human operator. As with all human inspection, repeatability, training, and capture rate are subject to flux. It has recently been discovered that wafer edge inspection is important for detecting delamination of thin films, chipping and cracking of the wafer, resist removal metrology, and particle detection, all of which cause yield issues in a modern fab. Furthermore, the edge of the wafer is a leading indicator of process status, and by monitoring the edge of the wafer for changes in appearance, tighter process control can be implemented.
One proposed solution includes laser/analog detector technology that looks directly at the edge normal of the wafer. This solution provides limited benefits in detecting particles and chip-outs, but is limited in classifying defects since the solution does not perform image processing. The market is looking for continued improvement in edge inspection.